Speaker device for sound reproduction in liquid medium

ABSTRACT

Apparatus for transducing electrical signal energy to acoustic energy for projection within liquid medium. Such speaker device consists of a sealed housing enclosure which is formed of resilient material such that it includes at least one generally planar side, and a permanent magnet cooperating with an electromagnetic drive coil are operatively disposed within said enclosure in suitable affixure to drive the planar side of the housing means so that it acts as the sound producing vibratile member in contact with the liquid medium.

United States Patent Kahn [451 June 13, 1972 [54] SPEAKER DEVICE FOR SOUND 2,879,496 3/1959 REPRODUCTION IN LIQUID MEDIUM [72] Inventor: Jay Dee C. Klll'ln, Yukon, .Okla. 1:526:414 2 1925 Du Bis Reymond 73 Ass LTV Lin Altec I Oklah C't I 1 Okla. 8 y Primary xaminerBenjamin A. Borchelt Assistant Examiner-H. A. Birmiel [22] i Mlflih 1970 Attorney-Dunlap, Laney, Hessin & Dougherty [21] Appl. No.: 22,623 ABSTRACT [52] U 8 CI 34018 R Uw 340/12 R Apparatus for transducing electrical signal energy to acoustic 340/14: energy for projection within liquid medium. Such speaker [51] Int Cl U00 device consists of a sealed housing enclosure which is formed 58] i I 79/] Uw of resilient material such that it includes at least one generally planar side, and a pennanem magnet cooperating with an electromagnetic drive coil are operatively disposed within said [56] Rekrcnm Cmd enclosure in suitable affixure to drive the planar side of the UNITED STATES PATENTS housing means so that it acts as the sound producing vibratile 3 027 541 3/l962 H 0H2 memberin contact with the liquid medium.

arrts 2,740,946 4/1956 Geneslay 6 Claims, 2 Drawing figures Q 88 72 9a 92 $555067?! 80 ?8 M f4 /8 7 2? .'6@'- ,r'rez. .3."- m

56 46 04 mo 5? 44 m2 SPEAKER DEVICE FOR SOUND REPRODUCTION IN LIQUID MEDIUM BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates generally to sound producing loudspeaker and, more particularly, but not by way of limitation, it relates to improved sound transducer apparatus for generating acoustic energy within a liquid medium.

2. Description of the Prior Art The prior art includes various types of mechanical reproducer for generating sound energy in a liquid or water medium. These are generally directed to the generation of pulse or selected frequencies of sound output energy as may be utilized in various surveillance and testing systems. Such prior underwater speakers or acoustic energy transducing devices range from conventional speaker design, having waterproofed vibratile members as utilized in short-range pulse-type communication, to large, high powered piston-type transducer elements, as are found in various marine geophysical prospecting applications.

SUMMARY OF THE INVENTION The present invention contemplates a sound reproducing device for generating acoustic energy in a water medium. In a more limited aspect, the invention consists of a sealed housing enclosure having a resilient, generally planar wall portion which is disposed to be driven to impart vibratile energy into the surrounding liquid medium. A permanent magnet struc ture is secured within the housing enclosure and arranged to define an air gap within which a spider-supported voice coil is suspended, and the other end of the voice coil is securely affixed to the resilient, planar portion of the housing enclosure such that electromagnetic drive of the voice coil imparts sound gene vibratile movement thereto.

Therefore, it is an object of the present invention to provide a speaker device which imparts sound energy within a water medium at much increased efficiency.

It is also an object of the invention to provide a sound generation device for use under water which is completely sealed against entry of surrounding water, even as against wicking, or absorption entry within the associated electrical supply cable.

Finally, it is an object of the present invention to provide a highly efficient, ruggedized underwater speaker device which, in addition to providing very good acoustic impedence match to a surrounding water medium, bears no exposable parts which are subject to corrosion, rust or other forms of decomposition due to effects of the surrounding medium.

Other objects and advantages of the invention will be evident from the following detailed description when read in conjunction with the accompanying drawing which illustrates the invention.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective view of the speaker device of the invention as utilized in a water medium; and

FIG. 2 is a side elevation of the water-adaptive speaker device with a portion shown in vertical cross section.

DETAILED DESCRIPTION OF THE INVENTION Referring to FIG. I a speaker assembly is disposed for sound reproduction within a liquid or water medium 12. The speaker assembly 10 is supplied with electrical actuating energy by means of a rubber-coated or otherwise sealed cable 14 which is connected from an external energizing source down into the water medium 12 for sealed entry into the rear side of speaker assembly 10, as will be further described below. The speaker assembly 10 consists of housing enclosure 16 which is unitarily formed to provide an annular mounting ring 18 having a plurality of mounting holes 20 disposed therearound. A generally planar portion 22 of housing enclosure 16 is adapted to serve as the vibratile element or sound producing member of the speaker assembly 10. The planar portion 22 actually serves as the coupling or drive element which imparts sound vibration into the surrounding water medium 12.

Referring now' to FIG. 2, the speaker assembly 10 is shown in greater detail with housing enclosure 16 being formed essentially by two generally cylindrical, concentrically engaged housing portions. Le. a front housing 24 and a rear housing 26. The front housing 24 is formed as a body of revolution which includes the planar end panel 22 which is unitarily joined to or formed with a circular wall 28 which extends to a further formation of an annular flange 30 and an outer or concentric side wall 32. The central portion of end panel 22 is formed to have a circular depression 34 formed within the inner side, this depression serving to aid in voice coil affixure as will be further described below.

The rear housing 26 is also a body of revolution formed unitarily to have a rear panel 36 which extends into a circular side wall 38 which, in turn, is outwardly formed or bent to form the mounting flange 18. A hole 40 is formed in the rear panel 36 to provide entry of the electrical supply cable 14 which provides drive power to the electromagnetic elements of the speaker assembly 10, as will be further described below. A rubber fitting or grommet 42 is adapted for insertion in panel hole 40 about cable 14 to provide water-tight sealing affixure.

The front housing 24 and rear housing 26 are formed of suitable resilient material which will allow front end panel 22 to act as the vibratile element or moving diaphragm which generates sound waves for transmission in the water medium 12. The front housing 24 and rear housing 26 are preferably formed from selected plastic material having desirable rigidity and resilency characteristics so that it provides good structural strength and, at the same time, can allow enough flexibility to maintain good sound energy coupling into the water medium 12. There are many of several groups of plastics which would be suitable for formation of respective front and rear housings 24 and 26, and one such plastic material which has been employed to good advantage is an ABS plastic known commercially as Marbon" resin. When this ABS plastic is used, a thickness of about 0.125 inches is found to give good operational results. Sealed joinder of the plastic front housing 24 and rear housing 26 is then carried out with solvent welding by application of a selected plastic solvent, one having proper solubility requirements relative to the structural plastic used, the solvent is then applied to the outer side of concentric side wall 32 and the inner side of rear side wall 38 to form a weld 44 upon joinder of housings 24 and 26. The weld 44 should be continuous around the speaker assembly 10 to assure watertight sealing of the inside of the speaker assembly 10.

The inner parts of speaker assembly 10 are supported from a mounting panel 46 of circular form which extends generally across the speaker assembly 10, and panel 46 is solvent welded, as is shown by weld 48, continuously about the inner side of annular flange 30. The panel 46 is formed with a central recess or cylindrical cup 50 which supports a pair of feedthrough solder contacts 52 and 54 therein. The solder contacts 52 and 54 are each solder connected to respective voice coil wire connectors 56 and 58 which extend from the voice coil as will be further described below. The contact ends of solder contacts 52 and 54 are then connected as by soldering to respective electrical supply wires 60 and 62 from within the cable 14. A third lead 64 from cable 14 may serve as a ground lead and as such it is connected to a suitable screw mounting 66.

A plurality of mounting screws 66 are inserted through panel 46 for threaded connection to secure a circular-shaped magnet structure 68 within the housing enclosure 16, the cylindrical cup 50 also providing a centering effect by its insertion within the center hole of annular magnet structure 68. The magnet structure 68 consists of an annular permanent magnet 70 as bonded between an upper annular pole piece 72 and a lower annular pole piece 74 which receives the mounting screws 66. A cylindrical pole piece 76 is secured as by force fit in firm engagement with the inner circular edge of lower annular pole piece 74, and cylindrical pole piece 76 extends upward to position a circular pole flange 78 in pre-determined spaced relationship to the inner circular edge 80 of upper annular pole piece 72. The circular spacing between circular flange 78 and inner edge 80 of pole piece 72 defines an air gap 81 within which a voice coil assembly 82 is suspended. in one form of the invention, the permanent magnet 70 is a l2.7 ounce ceramic magnet.

The voice coil assembly 82 is cylindrical in shape and it is securely afi'ixed to end panel 22 by bonding with a suitable epoxy resin 84 about the circular depression 34 in the under side of end panel 22. The voice coil assembly 82 is further supported as to proper centering and limiting of lateral movement within the magnet air gap 81 by means of a circular spider element 86. Spider element 86 may be a conventional type of molded fibrous structure having a circular mounting flange 88 which is suitably bonded about the upper surface of upper pole piece 72 with secure affixure as by suitable bonding of the inner circular edge 90 to the voice coil assembly 82.

The voice coil assembly 82 consists of a coil former 92, a suitable form of cylindrical, plastic form material, and an electrical actuating coil 94 of relatively fine guage wire conductor is wound about the lower end of former 92 to be supported within air gap 81. A pair of opposite end wire conductors from coil 94, shown generally as lead indication 96, are then brought up to approximately the position of weld-joinder of spider 86 to the coil former 92 whereupon each is soldered to a respective one of the wire connectors 56 and 58.

Further sealing is effected by addition of a suitable form of solidifying sealant 100 which is applied during the final stage of assembly to ensure sufficient sealing through out the interior of the speaker assembly 10. Such sealing is efi'ective even if external water should get through sealing grommet 42 into the rear space 102. The sealant 100 may be any of various suitable forms of sealing compound, and one such is known as Polyamide Copolymer Hot Melt Sealant which is commercially available from General Mills Corp. The sealant 100 is poured on top of mounting panel 46 to a sufficient depth that it encloses the end 104 of cable 14 while also completely closing all of individual supply leads 60 and 62, ground lead 64, and their respective contact elements. The practice of applying the hot melt sealant over end 104 of cable 14 is effected to guard against a condition known as wicking wherein water gaining entry at cable end 104 can seep, as by continuous absorption, upward along the insulating packing within cable 14. If wicking is present it is probable that an intolerable condition will arise at some time in the not too distant future.

in operation of speaker assembly 10, the unit can be suitably mounted in a selected underwater location, eg in a swimming pool. It should also be understood that it may be necessary to utilize a plurality of speaker assemblies to provide adequate and faithful sound reproduction coverage. Also, it may become necessary to carefully arrange and adjust the relative distances of separation and the sound projection directions of multiple speaker assemblies 10 to provide most uniform sound coverage in a body of water.

The energizing electrical signal may be such as a usual 8, 16 ohm or other related output impedence connection as provided via cable 14, energizing voltage being present as between lead wires 60 and 62. The energizing voltage is then applied through contacts 52 and 54 and connectors 56 and 58 for reaction in voice coil 94. Voice coil 94 then sets up varying electromagnetic field energy within the air gap 81 which, in turn, causes reciprocal motion of voice coil assembly 82 within air gap 81. Since voice coil 82 is rigidly secured to the inner depression 34 of end panel 22, the reciprocation of voice coil assembly 82 is transmitted to the end panel 22 to cause a similar vibration of end panel 22. Thus, end panel 22 couples the vibrations into the surrounding water medium 12 and, depending upon choice of resilient materials utilized in construction of housing enclosure 16 and end panel 22, such sound coupling is made with fairly high efficiency.

The speaker assembly 10 is sealed in very highly effective manner against entry of any water or moisture which might damage the interior working parts. Such sealing is effective to maintain the interior or speaker assembly 10 in safe, dry condition for a very long period of time. Such effective sealing is enabled by the utilization of solvent welding and hot melt sealants in joinder of unitarily formed components and elements.

In assembly, the forward housing 24 is inverted and liquid epoxy resin of suitable type is flowed into the depression 34 as centrally disposed in the inner surface of end panel 22. The voice coil assembly 82 is then inserted such that the upper end of coil former 92 is immersed in the epoxy within depression 34, whereupon the epoxy is allowed to cure thereby to provide tight affixure between end panel 22 and voice coil assembly 82. The necessary bonding cement and soldering contacts are then applied before placing the spider element 86 in position, and the lead connectors 56 and 58 are led through the soldering contacts 52 and 54. The magnet structure 68 is then secured to the underside of mounting panel 46 by means of a plurality of screws 66 whereupon it is then placed so that the outer circular edge of mounting panel 46 rests on annular flange 30. The circular air gap 81 will also then envelope the wire coil 94 of voice coil assembly 82, and a suitable solvent weld may be effected around the periphery of mounting panel 46 as shown by weld 48.

The assembly to this point is then inverted to rest with end panel 22 downward, and the liquid hot melt sealant I00 is poured in to fill the cylindrical cup 50 and a sufficient level above the mounting panel 46 to include the end 104 of cable 14. Thereafter, the rear housing 26 is fitted around the concentric side wall 32 and sealed by a suitable solvent weld, as denoted by weld 44. The weld should be continuous around the entire assembly in order to assure more effective sealing.

The foregoing discloses an underwater speaker device which is capable of being immersed for operation in a water medium for a long period of time without danger of corrosion or damage to either the housing enclosure or the internal drive components. The housing enclosure is constructed of mate rial which is inert to the surrounding substance, and the material is sufficiently resilient to enable use of an integrally formed end panel portion as a sound generating and coupling member in contact with the water medium. A speaker as constructed in accordance with the invention utilizes an integral end panel as the vibratile or diaphragm element thus to enable what is effectively an increased diaphragm area which can be driven to produce an equivalent acoustical output by proportionately smaller input power. Further, the stiff, rigid diaphragm or vibratile element is conducive to utilization of the speaker at much greater water pressures such that the invention can be used a greater depth.

Changes may be made in the combination and arrangement of elements as heretofore set forth in this specification and shown in the drawings; it being understood, that changes may be made in the embodiments disclosed without departing from the spirit and scope of the invention as defined in the following claims.

What is claimed is:

l. A device for electromagnetically reproducing acoustic energy within a liquid medium, comprising:

housing means formed of resilient material for disposition in immersion in said liquid medium, said housing means forming a water-tight enclosure having at least one side of generally planar form;

permanent magnet means secured within said housing means and defining a single continuous air gap which is disposed normal to and spaced from said housing means one side;

electromagnetic means consisting of coil former means and voice coil means formed about one edge thereof, said coil former means being securely affixed generally centrally to said housing means one side within said housing means enclosure to extend said voice coil means into position for variable disposition within said permanent magnet means air gap; and

conductor means receiving electrical energizing power and being connected to said voice coil means thereby to cause said varying disposition of said electromagnetic means and consequent movement of said housing means one side. 2. A device as set forth in claim 1 wherein said housing means comprises:

first housing enclosure of cylindrical form having one generally planar end and an open end and being unitarily formed of resilient material; and second enclosure means which is sealingly connected to close the open end of said first housing enclosure and which includes a feed-through orifice through which said conductor means passes. 3. A device as set forth in claim 1 which is further characterized in that:

said housing means is formed from a resilient plastic material. 4. A device as set forth in claim 1 wherein said permanent magnet means comprises:

annular magnet means including annular pole pieces which form a circular air gap.

5. A device as set forth in claim 2 which is further characterized to include:

plastic sealant completely sealing across the open cylindrical end of said first enclosure means and providing sealing compaction around said conductor means as connected through said feed-through orifice.

6. A device as set forth in claim 2 which is further characterized to include:

mounting panel means sealingly connected across the open end of said first enclosure means in parallel, spaced relationship to said end panel;

means mounting said permanent magnet means in rigid affixure to said mounting panel means for support thereon; and

waterproof sealing means disposed on the other side of said mounting panel from said permanent magnet means and completely sealing across said first enclosure open end and providing sealing contact around said conductor means.

III I? i II 

1. A device for electromagnetically reproducing acoustic energy within a liquid medium, comprising: housing means formed of resilient material for disposition in immersion in said liquid medium, said housing means forming a water-tight enclosure having at least one side of generally planar form; permanent magnet means secured within said housing means and defining a single continuous air gap which is disposed normal to and spaced from said housing means one side; electromagnetic means consisting of coil former means and voice coil means formed about one edge thereof, said coil former means being securely affixed generally centrally to said housing means one side within said housing means enclosure to extend said voice coil means into position for variable disposition within said permanent magnet means air gap; and conductor means receiving electrical energizing power and being connected to said voice coil means thereby to cause said varying disposition of said electromagnetic means and consequent movement of said housing means one side.
 2. A device as set forth in claim 1 wherein said housing means comprises: first housing enclosure of cylindrical form having one generally planar end and an open end and being unitarily formed of resilient material; and second enclosure means which is sealingly connected to close the open end of said first housing enclosure and which includes a feed-through orifice through which said conductor means passes.
 3. A device as set forth in claim 1 which is further characterized in that: said housing means is formed from a resilient plastic material.
 4. A device as set forth in claim 1 wherein said permanent magnet means comprises: annular magnet means including annular pole pieces which form a circular air gap.
 5. A device as set forth in claim 2 which is further characterized to include: plastic sealant completely sealing across the open cylindrical end of said first enclosure means and providing sealing compaction around said conductor means as connected through said feed-through orifice.
 6. A device as set forth in claim 2 which is further characterized to include: mounting panel means sealingly connected across the open end of said first enclosure means in parallel, spaced relationship to said end panel; means mounting said permanent magnet means in rigid affixure to said mounting panel means for support thereon; and waterproof sealing means disposed on the other side of said mounting panel from said permanent magnet means and completely sealing across said first enclosure open end and providing sealing contact around said conductor means. 